Substrate processing apparatus and substrate processing method

ABSTRACT

A rinsing liquid (DIW) is discharged from a rinsing liquid discharge port formed in a blocking member to perform rinsing processing to a substrate surface while a nitrogen gas is supplied into a clearance space, and a liquid mixture (IPA+DIW) is discharged from a liquid mixture discharge port formed in the blocking member to replace the rinsing liquid adhering to the substrate surface with the liquid mixture while the nitrogen gas is supplied into the clearance space. Thus, an increase of the dissolved oxygen concentration of the liquid mixture can be suppressed upon replacing the rinsing liquid adhering to the substrate surface with the liquid mixture, which makes it possible to securely prevent from forming an oxide film or generating watermarks on the substrate surface.

CROSS REFERENCE TO RELATED APPLICATION

The present application is a divisional application of Ser. No.13/336,729 filed Dec. 23, 2011, which is a divisional of U.S. Ser. No.11/860,173 filed Sep. 24, 2007, which application claims benefit andpriority of Japanese Application No. 2006-265137 filed Sep. 28, 2006which are all incorporated herein in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a substrate processing apparatus and asubstrate processing method for applying a predetermined wet processingto a substrate surface by supplying a processing liquid to the substratesurface, and then, drying the substrate surface wet with the processingliquid. Substrates to be dried include semiconductor wafers, glasssubstrates for photomasks, glass substrates for liquid crystal displays,glass substrates for plasma displays, substrates for FEDs (fieldemission displays), substrates for optical discs, substrates formagnetic discs, and substrates for magnet-optical discs.

2. Description of the Related Art

Numerous drying methods have already been proposed which aim at removalof a rinsing liquid adhering to a substrate surface after chemicalprocessing using a chemical solution and rinsing processing using arinsing liquid which may be pure water or the like. Known as one suchmethod is a drying method which uses a liquid (low surface tensionsolvent) including an organic solvent component whose surface tension islower than pure water such as IPA (isopropyl alcohol). There is a dryingmethod described in JP-A-9-38595 for instance as such a drying method.In a substrate processing apparatus which executes this drying method,after hydrofluoric acid treatment of a substrate surface, pure water issupplied to the substrate surface and cleaning processing (rinsingprocessing) is accordingly attained. Following this, IPA is supplied tothe substrate surface without any break after the end of the supply ofpure water or from the middle of the supply of pure water. Inconsequence, IPA is dissolved in pure water which is present on thesubstrate surface, and replaces pure water. The substrate is rotated ata high speed thereafter, which removes IPA from the substrate surfaceand the substrate surface is dried.

Further, according to a resist developing method described inJP-A-3-209715, the substrate surface is dried while the amount of microforeign matters present on the substrate surface is reduced in thefollowing manner. First, pure water is supplied to the substrate afterdevelopment of a resist, thereby performing pure water cleaning (rinsingprocessing). After this, pure water containing IPA at the capacity ratioof about 10% (IPA solution) is supplied to the substrate, whereby thesubstrate is cleaned. This is followed by spin drying of the substratewhile rotating the substrate at a high speed.

SUMMARY OF THE INVENTION

Incidentally, in order to replace the pure water on the substratesurface with IPA or IPA solution after rinsing processing, IPA or IPAsolution needs to be fed to the respective parts of the substratesurface. Hence, when replacing processing by means of IPA or IPAsolution is performed, a liquid (low surface-tension solvent) having alower surface tension than the pure water is fed to the respective partsof the pure water adhering to the substrate surface. Then, a convectiveflow (Marangoni convective flow) is induced based on a surface tensiondifference between the pure water and the low surface-tension solvent atthe respective parts of the substrate surface. This promotes theagitation of the liquid on the substrate surface, thereby increasing achance of the liquid on the substrate surface being exposed to ambientenvironment (air). As a result, the dissolved oxygen concentration ofthe liquid (IPA or IPA solution) adhering to the substrate surfaceincreases as replacing processing proceeds, and the substrate surface isentirely or partly oxidized, which has caused a problem of forming anoxide film or generating watermarks on the substrate surface.

An object of the present invention is to satisfactorily dry a substratesurface while preventing the generation of watermarks on the substratesurface in a substrate processing apparatus and a substrate processingmethod for drying the substrate surface wet with a processing liquidusing a low surface-tension solvent such as IPA.

According to a first aspect of the present invention, there is provideda substrate processing apparatus, comprising: a substrate holder whichholds a substrate in a substantially horizontal posture; a substraterotating unit which rotates the substrate held by the substrate holderabout a predetermined rotation axis; a blocking member which includes aprocessing liquid discharge port and a solvent discharge port whichrespectively discharge a processing liquid and a low surface-tensionsolvent having a lower surface tension than the processing liquid to acentral part of a surface of the substrate held by the substrate holder,and is arranged away from the substrate surface while facing thesubstrate surface; a gas supplier which supplies an inert gas into aclearance space defined between the blocking member and the substratesurface, wherein after supplying the processing liquid to the substratesurface to perform predetermined wet processing to the substratesurface, the low surface-tension solvent is supplied to the substratesurface, and then the low surface-tension solvent is removed from thesubstrate surface to dry the substrate surface, the processing liquid isdischarged from the processing liquid discharge port to perform the wetprocessing while the gas supplier supplies the inert gas into theclearance space, and the low surface-tension solvent is discharged fromthe solvent discharge port to replace the processing liquid adhering tothe substrate surface with the low surface-tension solvent while the gassupplier supplies the inert gas into the clearance space.

According to a second aspect of the present invention, there is provideda substrate processing method, comprising: a blocking-member arrangingstep of arranging a blocking member away from a substrate surface whilefacing the substrate surface, the blocking member including a processingliquid discharge port and a solvent discharge port which respectivelydischarge a processing liquid and a low surface-tension solvent having alower surface tension than the processing liquid to a central part ofthe surface of a substrate which is held in a substantially horizontalposture; a wet processing step of discharging the processing liquid fromthe processing liquid discharge port to the substrate surface while thesubstrate is rotated to perform predetermined wet processing to thesubstrate surface; a replacing step of discharging the lowsurface-tension solvent from the solvent discharge port to the substratesurface wet with the processing liquid while the substrate is rotated toreplace the processing liquid adhering to the substrate surface with thelow surface-tension solvent; and a drying step of removing the lowsurface-tension solvent from the substrate surface after the replacingstep to dry the substrate surface, wherein an inert gas is supplied, inthe wet processing step and the replacing step, into a clearance spacedefined between the blocking member arranged in the blocking-memberarranging step and the substrate surface.

In each of these inventions, the blocking member is arranged away fromthe substrate surface while facing the substrate surface, and the inertgas is supplied into the clearance space defined between the blockingmember and the substrate surface. The processing liquid is dischargedfrom the processing liquid discharge port formed in the blocking memberto perform the predetermined wet processing while the inert gas issupplied into the clearance space, and the low surface-tension solventis discharged from the solvent discharge port to replace the processingliquid adhering to the substrate surface with the low surface-tensionsolvent while the inert gas is supplied into the clearance space.Accordingly, the wet processing with the processing liquid and thereplacing processing with the low surface-tension solvent are performedwhile the ambient atmosphere of the substrate surface is maintained tobe a low oxygen concentration atmosphere. Thus, the dissolution ofoxygen into the low surface-tension solvent from the ambient atmosphereof the substrate surface can be reduced upon replacing the processingliquid adhering to the substrate surface with the low surface-tensionsolvent. As a result, an increase of the dissolved oxygen concentrationof the low surface-tension solvent can be suppressed, and hence, it ispossible to securely prevent from forming an oxide film or generatingwatermarks on the substrate surface. Further, since the inert gasatmosphere is set in the clearance space while the blocking member iscaused to face the substrate surface, the splash of the processingliquid or the low surface-tension solvent removed from the substratesurface back to the substrate surface can be suppressed. Therefore, theadherence of particles to the substrate surface can be reduced.

The above and further objects and novel features of the invention willmore fully appear from the following detailed description when the sameis read in connection with the accompanying drawing. It is to beexpressly understood, however, that the drawing is for purpose ofillustration only and is not intended as a definition of the limits ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing a first embodiment of a substrate processingapparatus according to the invention.

FIG. 2 is a block diagram showing a main control construction of thesubstrate processing apparatus of FIG. 1.

FIG. 3 is a vertical sectional view showing an essential portion of ablocking member equipped in the substrate processing apparatus of FIG.1.

FIG. 4 is a sectional view (horizontal sectional view) taken on line A-Aof FIG. 3.

FIG. 5 is a flow chart showing the operation of the substrate processingapparatus of FIG. 1.

FIG. 6 is a timing chart which shows the operation of the substrateprocessing apparatus shown in FIG. 1.

FIGS. 7A and 7B are diagrams schematically showing the operation of thesubstrate processing apparatus of FIG. 1.

FIGS. 8A to 8C are diagrams schematically showing the operation of thesubstrate processing apparatus of FIG. 1.

FIG. 9 is a graph showing the relationship between the IPA concentrationand surface tension y.

FIG. 10 is a timing chart showing the operation of a substrateprocessing apparatus according to a second embodiment of the invention.

FIGS. 11A to 11C are diagrams schematically showing the operation of thesubstrate processing apparatus according to the second embodiment of theinvention.

FIG. 12 is a diagram showing a third embodiment of a substrateprocessing apparatus according to the invention.

DETAILED DESCRIPTION First Embodiment

FIG. 1 is a diagram showing a first embodiment of a substrate processingapparatus according to this invention, and FIG. 2 is a block diagramshowing a main control construction of the substrate processingapparatus of FIG. 1. This substrate processing apparatus is a substrateprocessing apparatus of a single wafer type used for cleaning processingto remove undesired substance adhering to a surface Wf of a substrate Wsuch as a semiconductor wafer. More specifically, after applyingchemical processing using a chemical solution such as a hydrofluoricacid and rinsing processing using a rinsing liquid such as pure water orDIW (deionized water) to the substrate surface Wf, this apparatus driesthe substrate surface Wf wet with the rinsing liquid. In thisembodiment, the substrate surface Wf means a pattern-formed surface onwhich a device pattern made of poly-Si or the like is formed.

This substrate processing apparatus includes a spin chuck 1, a chemicalsolution discharging nozzle 3, and a blocking member 9. The spin chuck 1holds the substrate W in a substantially horizontal posture with thesubstrate surface Wf faced up and rotates the substrate W. The chemicalsolution discharging nozzle 3 discharges a chemical solution toward thesurface Wf of the substrate W held by the spin chuck 1. The blockingmember 9 is disposed at a position above the spin chuck 1.

The spin chuck 1 has a rotary spindle 11 linked to a rotary shaft of achuck rotating mechanism 13 including a motor, and is rotatable about arotation axis J (vertical axis) by driving the chuck rotating mechanism13. These rotary spindle 11 and chuck rotating mechanism 13 are housedin a cylindrical casing 2. A disk-shaped spin base 15 is integrallyconnected to the upper end of the rotary spindle 11 by means of afastening part such as a screw. Accordingly, the spin base 15 rotatesabout the rotation axis J by driving the chuck rotating mechanism 13 inaccordance with an operation command from a control unit 4 whichcontrols the entire apparatus. Thus, in this embodiment, the chuckrotating mechanism 13 functions as a “substrate rotating unit” of theinvention.

Plural chuck pins 17 for holding the substrate W at the rim thereof aredisposed upright in the vicinity of the rim of the spin base 15. Ittakes not less than three chuck pins 17 to securely hold the disk-shapedsubstrate W, and the chuck pins 17 are arranged at equal angularintervals along the rim of the spin base 15. Each chuck pin 17 comprisesa substrate support part which supports the substrate W at the rimthereof from below and a substrate holding part which presses thesubstrate W at the outer circumferential edge surface thereof to holdthe substrate W. Each chuck pin 17 is structured so as to be capable ofswitching between a pressing state that the substrate holding partpresses the substrate W at the outer circumferential edge surfacethereof and a released state that the substrate holding part stays awayfrom the outer circumferential edge surface of the substrate W.

The plural chuck pins 17 are in the released state while the substrate Wis being transferred to the spin base 15 but in the pressing state forcleaning of the substrate W. When in the pressing state, the pluralchuck pins 17 hold the substrate W at the rim thereof and keep thesubstrate approximately horizontally at a predetermined distance fromthe spin base 15. The substrate W is held with its front surface(pattern-formed surface) Wf directed toward above and its back surfaceWb toward below. Thus, in this embodiment, the chuck pins 17 function asa “substrate holder” of the invention. The substrate holder is notlimited to the chuck pins 17, and a vacuum chuck which supports thesubstrate W by sucking the substrate back surface Wb may be used.

The chemical solution discharging nozzle 3 is connected with a chemicalsolution supplying source via a chemical solution valve 31. Hence, whenthe chemical solution valve 31 opens or closes based on a controlcommand from the control unit 4, the chemical solution is pressure-fedfrom the chemical solution supplying source toward the chemical solutiondischarging nozzle 3, and the chemical solution discharging nozzle 3discharges the chemical solution. Meanwhile, hydrofluoric acid, BHF(buffered hydrogen fluoride), or the like is used as the chemicalsolution. Further, the chemical solution discharging nozzle 3 isconnected with a nozzle moving mechanism 33 (FIG. 2). The nozzle movingmechanism 33 is driven in response to an operation command from thecontrol unit 4, hence, the chemical solution discharging nozzle 3reciprocally moves between a discharge position which is above thecenter of rotation of the substrate W and a stand-by position which isoff the discharge position to the side.

The blocking member 9 includes a plate-like member 90, a rotary spindle91 which is hollow inside and supports the plate-like member 90, and aninner inserted shaft 95 which is inserted in a hollow part of the rotaryspindle 91. The plate-like member 90 is a disk-shaped member having anaperture in the center, and opposed to the surface Wf of the substrate Wheld by the spin chuck 1. A lower surface (bottom surface) 90 a of theplate-like member 90 serves as a substrate facing surface which facesthe substrate surface Wf substantially in parallel, and is formed tohave a planar size equal to or larger than the diameter of the substrateW. The plate-like member 90 is substantially horizontally mounted on thebottom end of the rotary spindle 91 having a substantially cylindricalshape, and the rotary spindle 91 is so held by a horizontally extendingarm 92 as to be rotatable about the rotation axis J passing the centerof the substrate W. A bearing (not shown) is mounted between the outercircumferential surface of the inner inserted shaft 95 and the innercircumferential surface of the rotary spindle 91. A blocking-memberrotating mechanism 93 and a blocking-member elevating mechanism 94 areconnected with the arm 92.

The blocking-member rotating mechanism 93 rotates the rotary spindle 91about the rotation axis J in accordance with an operation command fromthe control unit 4. When the rotary spindle 91 is rotated, theplate-like member 90 integrally rotates with the rotary spindle 91. Theblocking-member rotating mechanism 93 is constructed to rotate theplate-like member 90 (lower surface 90 a) in the same direction andsubstantially at the same speed as the substrate W as the substrate Wheld by the spin chuck 1 rotates. Thus, in this embodiment, theblocking-member rotating mechanism 93 functions as a “blocking-memberrotating unit” of the invention.

The blocking-member elevating mechanism 94 moves the blocking member 90close and opposed to the spin base 15 and, conversely, moves theblocking member 90 away from the spin base 15 in accordance with anoperation command from the control unit 4. Specifically, by activatingthe blocking-member elevating mechanism 94, the control unit 4 causesthe blocking member 9 to move up to a separated position above the spinchuck 1 upon loading and unloading the substrate W into and from thesubstrate processing apparatus. On the other hand, the control unit 4causes the blocking member 9 to move down to a predetermined facingposition (position shown in FIG. 1) set right in the vicinity of thesurface Wf of the substrate W held by the spin chuck 1 upon applyingpredetermined processing to the substrate W. In this embodiment, theblocking member 9 is lowered from the separated position to the facingposition after the start of rinsing processing and kept at the facingposition until drying processing is completed.

FIG. 3 is a vertical sectional view showing an essential portion of ablocking member equipped in the substrate processing apparatus of FIG.1, and FIG. 4 is a sectional view (horizontal sectional view) taken online A-A of FIG. 3. The inner inserted shaft 95 inserted in the hollowpart of the rotary spindle 91 has a circular horizontal section. This isfor equally holding a clearance between the inner inserted shaft(non-rotary member) 95 and the rotary spindle (rotary member) 91 overthe entire circumference, and the clearance between the inner insertedshaft 95 and the rotary spindle 91 is sealed from the outside byintroducing a sealing gas thereinto. The inner insertion shaft 95 isformed with three fluid supply passages extending in vertical direction.More specifically, a rinsing liquid supply passage 96, a liquid mixturesupply passage 97, and a gas supply passage 98 are formed in the innerinserted shaft 95. The rinsing liquid supply passage 96 is a passage forthe rinsing liquid. The liquid mixture supply passage 97 is a passagefor a liquid mixture (corresponding to a “low surface-tension solvent”of the invention) in which a liquid having the same composition as therinsing liquid and an organic solvent component to be dissolved in theliquid to lower the surface tension are mixed. The gas supply passage 98is a passage for an inert gas such as a nitrogen gas. The rinsing liquidsupply passage 96, the liquid mixture supply passage 97 and the gassupply passage 98 are formed by respectively inserting tubes 96 b, 97 band 98 b made of PFA (perfluoroalkylvinylether copolymer) into the innerinserted shaft 95 made of PTFE (polytetrafluoroethylene).

The bottom ends of the rinsing liquid supply passage 96, the liquidmixture supply passage 97 and the gas supply passage 98 respectivelyserve as a rinsing liquid discharge port 96 a (corresponding to a“processing liquid discharge port” of the invention), a liquid mixturedischarge port 97 a (corresponding to a “solvent discharge port” of theinvention), and a gas discharge port 98 a, and face the surface Wf ofthe substrate W held by the spin chuck 1. In this embodiment, thediameter of the inner inserted shaft is 18 to 20 mm. The bore diametersof the rinsing liquid discharge port 96 a, the liquid mixture dischargeport 97 a and the gas discharge port 98 a are 4 mm, 2 to 3 mm and 4 mm,respectively. In this way, the bore diameter of the liquid mixturedischarge port 97 a is smaller than that of the rinsing liquid dischargeport 96 a in this embodiment. This can prevent the following problems.Specifically, the liquid mixture (IPA+DIW) has a lower surface tensionthan the rinsing liquid (DIW). Thus, if the liquid mixture is dischargedthrough a liquid mixture discharge port having the same bore diameter asthe rinsing liquid discharge port, there is a likelihood that the liquidmixture drops from the liquid mixture discharge port after the dischargeof the liquid mixture is stopped. On the other hand, if the rinsingliquid is discharged through a rinsing liquid discharge port having thesame bore diameter as a liquid mixture discharge port, the dischargespeed of the rinsing liquid is too fast. As a result, the rinsing liquid(DIW) that is an electrical insulator collides with the substratesurface Wf at a relatively high speed, thereby making it possible thatsupplied parts of the substrate surface Wf to which the rinsing liquidis directly supplied are charged and oxidized. Contrary to this, in thisembodiment, separate discharge ports are provided for the liquid mixtureand the rinsing liquid, and the bore diameter of the liquid mixturedischarge port 97 a is smaller than that of the rinsing liquid dischargeport 96 a. Thus, the liquid mixture is prevented from dropping from theliquid mixture discharge port and an increase in the discharge speed ofthe rinsing liquid from the rinsing liquid discharge port is suppressed,whereby the oxidation of the substrate surface Wf caused by charging canbe suppressed.

Further, in this embodiment, the rinsing liquid discharge port 96 a isprovided at a position displaced from the central axis of the blockingmember 9, that is, at a position displaced radially outward from therotation axis J of the substrate W. This can avoid the rinsing liquiddischarged from the rinsing liquid discharge port 96 a being supplied insuch a manner as to concentrate on one point of the substrate surface Wf(rotation center WO of the substrate W). As a result, charged parts ofthe substrate surface Wf can be scattered and the oxidation of thesubstrate W caused by charging can be reduced. On the other hand, if therinsing liquid discharge port 96 a is excessively distanced from therotation axis J, it becomes difficult for the rinsing liquid to reachthe rotation center WO of the substrate surface Wf Accordingly, in thisembodiment, distance L from the rotation axis J to the rinsing liquiddischarge port 96 a (discharge port center) in horizontal direction isset at about 4 mm. Here, an upper limit of the distance L at which therinsing liquid (DIW) can be supplied to the rotation center WO of thesubstrate surface Wf is 20 mm on the following conditions.

-   -   Flow rate of DIW: 2 L/min    -   Number of revolutions of substrate: 1500 rpm    -   State of substrate surface: central part of surface is a        hydrophobic surface

An upper limit of distance from the rotation axis J to the liquidmixture discharge port 97 a (discharge port center) is basically thesame as the upper limit (20 mm) of the distance L from the rotation axisJ to the rinsing liquid discharge port 96 a (discharge port center) aslong as the number of revolutions of the substrate is set at 1500 rpm.

On the other hand, distance from the rotation axis J to the gasdischarge port 98 a (discharge port center) can be arbitrarily setwithout being particularly limited as long as a nitrogen gas can besupplied into a clearance space SP defined between the blocking member 9(plate-like member 90) positioned at the facing position and thesubstrate surface Wf. However, the gas discharge port 98 a is preferablyprovided on the rotation axis J or at a position proximate thereto fromthe standpoint of blowing the nitrogen gas to a solvent layer of theliquid mixture formed on the substrate surface Wf to remove the solventlayer from the substrate W as described later.

Further, a space portion defined between the inner wall surface of therotary spindle 91 and the outer wall surface of the inner inserted shaft95 forms an outer gas supply passage 99, the bottom end of which servesas an annular outer gas discharge port 99 a. In other words, theblocking member 9 is formed with the outer gas discharge port 99 a inaddition to the gas discharge port 98 a for discharging the nitrogen gastoward the central part of the substrate surface Wf, the outer gasdischarge port 99 a being located radially outward of the rinsing liquiddischarge port 96 a, the liquid mixture discharge port 97 a and the gasdischarge port 98 a and surrounding the rinsing liquid discharge port 96a, the liquid mixture discharge port 97 a and the gas discharge port 98a. The aperture area of this outer gas discharge port 99 a is formedconsiderably larger than that of the gas discharge port 98 a. Since theblocking member 9 is provided with two kinds of gas discharge ports inthis way, the nitrogen gas can be discharged at different flow rates andflow velocities from the respective discharge ports. For example, (1) itis preferable to supply the nitrogen gas at a relatively large flow rateand a low flow velocity so as not to blow the liquid on the substratesurface Wf in order to maintain an inert gas atmosphere as the ambientatmosphere of the substrate surface Wf On the other hand, (2) it ispreferable to supply the nitrogen gas at a relatively small flow rateand a high flow velocity to the central part of the surface of thesubstrate W upon removing the solvent layer of the liquid mixture formedon the substrate surface Wf from the substrate surface Wf Accordingly,the nitrogen gas is mainly discharged from the outer gas discharge port99 a in the case (1) and the nitrogen gas is mainly discharged from thegas discharge port 98 a in the case (2), whereby the nitrogen gas can besupplied toward the substrate surface Wf at suitable flow rate and flowvelocity depending on the usage of the nitrogen gas.

Further, the leading end (bottom end) of the inner inserted shaft 95 isnot flush with the lower surface 90 a of the plate-like member 90, andis retracted upward from the same plane including the lower surface 90 a(FIG. 3). According to such a construction, the nitrogen gas dischargedfrom the gas discharge port 98 a can be diffused to decrease the flowvelocity thereof to a certain degree by the time the nitrogen gasreaches the substrate surface Wf Specifically, if the flow velocity ofthe nitrogen gas from the gas discharge port 98 a is too fast, itinterferes with the nitrogen gas from the outer gas discharge port 99 a,making it difficult to remove the solvent layer of the liquid mixture onthe substrate surface Wf from the substrate W. As a result, liquid dropsremain on the substrate surface Wf. Contrary to this, according to theabove construction, the flow velocity of the nitrogen gas from the gasdischarge port 98 a can be moderated to reliably remove the solventlayer of the liquid mixture on the substrate surface Wf from thesubstrate W.

Referring back to FIG. 1, description continues. The upper end of therinsing liquid supply passage 96 is connected to a DIW supplying sourceformed by utilities of a plant and the like via a rinsing liquid valve83, and DIW can be discharged as a rinsing liquid from the rinsingliquid discharge port 96 a by opening the rinsing liquid valve 83.

Further, the upper end of the liquid mixture supply passage 97 isconnected to a liquid mixture supply unit 7. The liquid mixture supplyunit 7 includes a cabinet part 70 for producing the liquid mixture(organic solvent component+DIW) and can pressure-feed the liquid mixtureproduced in the cabinet part 70 to the liquid mixture supply passage 97.A substance to be dissolved in DIW (surface tension: 72 mN/m) and reducethe surface tension, e.g. isopropyl alcohol (surface tension: 21 to 23mN/m) is used as the organic solvent component. The organic solventcomponent is not limited to isopropyl alcohol (IPA), and various otherorganic solvent components such as ethyl alcohol and methyl alcohol maybe used. Further, the organic solvent component is not limited to aliquid, and vapors of various alcohols may be dissolved in DIW asorganic solvent components to produce a liquid mixture.

The cabinet part 70 comprises a reservoir tank 72 which holds the liquidmixture of DIW and IPA. The reservoir tank 72 accepts one end of a DIWintroducing pipe 73 which is for supplying DIW into inside the reservoirtank 72, and the other end of the DIW introducing pipe 73 is connectedvia an on-off valve 73 a with the DIW supplying source. Further, aflowmeter 73 b is inserted in midstream of the DIW introducing pipe 73and measures the flow rate of DIW which is led to the reservoir tank 72from the DIW supplying source. Based on the flow rate which theflowmeter 73 b measures, the control unit 4 controls opening and closingof the on-off valve 73 a so that the flow rate of DIW flowing in the DIWintroducing pipe 73 would be a target flow rate (target value).

In a similar manner, the reservoir tank 72 accepts one end of an IPAintroducing pipe 74 which is for supplying the IPA liquid into insidethe reservoir tank 72, and the other end of the IPA introducing pipe 74is connected via an on-off valve 74 a with an IPA supplying source.Further, a flowmeter 74 b is inserted in midstream of the IPAintroducing pipe 74 and measures the flow rate of the IPA liquid whichis led to the reservoir tank 72 from the IPA supplying source. Based onthe flow rate which the flowmeter 74 b measures, the control unit 4controls opening and closing of the on-off valve 74 a so that the flowrate of the IPA liquid flowing in the IPA introducing pipe 74 would be atarget flow rate (target value).

In this embodiment, the flow rates of IPA liquid and DIW introduced intothe reservoir tank 72 are regulated such that a percentage by volume ofIPA in the liquid mixture (hereinafter called “IPA concentration”) takesa predetermined value lying within a range equal to or below 50%, e.g.the IPA concentration becomes 10%. By setting the IPA concentration inthis way, the destruction of a pattern formed on the substrate surfaceWf can be efficiently prevented while the consumed amount of IPA issuppressed as described later. Further, measures to prevent exposure toIPA of the apparatus can be simplified as compared to 100% of IPA.

The other end of a liquid mixture supply pipe 75 having one end thereofconnected with the liquid mixture supply passage 97 is inserted into thereservoir tank 72, so that the liquid mixture stored in the reservoirtank 72 can be supplied to the liquid mixture supply passage 97 via aliquid mixture valve 76. A constant rate pump 77 for supplying theliquid mixture stored in the reservoir tank 72 to the liquid mixturesupply pipe 75, a temperature regulator 78 for regulating thetemperature of the liquid mixture supplied to the liquid mixture supplypipe 75 by the constant rate pump 77, and a filter 79 for removingforeign matters in the liquid mixture are provided in the liquid mixturesupply pipe 75. Further, a concentration meter 80 for monitoring the IPAconcentration is provided in the liquid mixture supply pipe 75.

Further, one end of a liquid mixture circulation pipe 81 branches outfrom the liquid mixture supplying pipe 75 between the liquid mixturevalve 76 and the concentration meter 80, and the other end of the liquidmixture circulation pipe 81 is connected with the reservoir tank 72. Acirculation valve 82 is inserted in the liquid mixture circulation pipe81. During the operation of the apparatus, the constant rate pump 77 andthe temperature adjuster 78 are driven all the time, whereas while theliquid mixture is not supplied to the substrate W, the liquid mixturevalve 76 is closed and the circulation valve 82 is opened. In this way,the liquid mixture which is pumped out by the constant rate pump 77 fromthe reservoir tank 72 returns back to the reservoir tank 72 via theliquid mixture circulation pipe 81. In short, when the liquid mixture isnot supplied to the substrate W, the liquid mixture circulates in thecirculation path composed of the reservoir tank 72, the liquid mixturesupplying pipe 75 and the liquid mixture circulation pipe 81. Meanwhile,at the timing for supplying the liquid mixture to the substrate W, theliquid mixture valve 76 is opened and the circulation valve 82 isclosed. This provides the liquid mixture supply passage 97 with theliquid mixture which is pumped out from the reservoir tank 72. In thisway, by circulating the liquid mixture while it is not supplied to thesubstrate W, DIW and IPA get agitated, realizing a state that DIW andIPA are adequately mixed with each other. In addition, it is possible toquickly supply after the liquid mixture valve 76 is opened to the liquidmixture supply passage 97 the liquid mixture whose temperature isregulated to a predetermined temperature and which is free from foreignmatters.

The upper ends of the gas supply passage 98 and the outer gas supplypassage 99 are respectively connected with a gas supply unit 18 (FIG.2), so that the nitrogen gas can be individually pressure-fed from thegas supply unit 18 to the gas supply passage 98 and the outer gas supplypassage 99 in accordance with an operation command from the control unit4. This enables the nitrogen gas to be supplied into the clearance spaceSP defined between the blocking member 9 (plate-like member 90)positioned at the facing position and the substrate surface Wf. Thus, inthis embodiment, the gas supply unit 18 functions as a “gas supplier” ofthe invention.

Fixed around the casing 2 is a receiver member 21. Cylindrical partitionmembers 23 a, 23 b and 23 c are disposed upright in the receiver member21. The space between the outer wall of the casing 2 and the inner wallof the partition member 23 a defines a first liquid drainage bath 25 a,the space between the outer wall of the partition member 23 a and theinner wall of the partition member 23 b defines a second liquid drainagebath 25 b, and the space between the outer wall of the partition member23 b and the inner wall of the partition member 23 c defines a thirdliquid drainage bath 25 c.

Vents 27 a, 27 b and 27 c are formed in bottom portions of the firstliquid drainage bath 25 a, the second liquid drainage bath 25 b and thethird liquid drainage bath 25 c, respectively, and the respective ventsare connected to different drains from each other. In this embodimentfor instance, the first liquid drainage bath 25 a is a bath forcollecting the chemical solution after use and is communicated with acollection drain which collects the chemical solution for reuse.Meanwhile, the second liquid drainage bath 25 b is a bath for drainingthe rinsing liquid after use and is communicated with a waste drainwhich is for disposal. Further, the third liquid drainage bath 25 c is abath for draining the liquid mixture after use and is communicated witha waste drain which is for disposal.

A splash guard 6 is disposed above the respective liquid drainage baths25 a through 25 c. The splash guard 6 is arranged so as to surround thesubstrate W which is held horizontally by the spin chuck 1 and to freelyascend and descend in a direction of the rotation axis J of the spinchuck 1. The shape of the splash guard 6 is approximatelyrotational-symmetric to the rotation axis J of the spin chuck 1. Thesplash guard 6 comprises three guards 61, 62 and 63 which are arrangedfrom the inward side to the outward side in a radial direction in aconcentric layout with respect to the spin chuck 1. The three guards 61,62 and 63 are progressively lower in the order from the outermost guard63 to the innermost guard 61, and the top ends of the respective guards61, 62 and 63 are aligned in the same plane which extends in thevertical direction.

The splash guard 6 is connected with a guard elevating mechanism 65 sothat when an elevator driving actuator (which may for instance be an aircylinder) of the guard elevating mechanism 65 operates in response to anoperation command from the control unit 4, the splash guard 6 moves upand down relative to the spin chuck 1. In this embodiment, since thesplash guard 6 ascends or descends stepwise when the guard elevatingmechanism 65 is driven, the processing liquid splashing from therotating substrate W is drained, split into the first through the thirdliquid drainage baths 25 a through 25 c.

An upper section of the guard 61 includes a groove-like first guidingpart 61 a which is open toward inside and is wedge-shaped (V-shaped) incross section. With the splash guard 6 set to the highest position(which will hereinafter be referred to as the “first height position”)during chemical processing, the chemical solution splashing from therotating substrate W is caught by the first guiding part 61 a and guidedinto the first liquid drainage bath 25 a. Describing this in morespecific details, when the splash guard 6 is at the first heightposition so that the first guiding part 61 a surrounds the substrate Wwhich is held by the spin chuck 1, the chemical solution splashing fromthe rotating substrate W is guided into the first liquid drainage bath25 a via the guard 61.

Meanwhile, an upper section of the guard 62 includes a slanted part 62 awhich is tilted diagonally upward from the outward side to the inwardside in the radial direction. With the splash guard 6 set to a lowerposition than the first height position (which will hereinafter bereferred to as the “second height position”) during rinsing processing,the rinsing liquid splashing from the rotating substrate W is caught bythe slanted part 62 a and guided into the second liquid drainage bath 25b. To be more specific, when the splash guard 6 is at the second heightposition so that the slanted part 62 a surrounds the substrate W whichis held by the spin chuck 1, the rinsing liquid splashing from therotating substrate W drops between the top end of the guard 61 and thetop end of the guard 62 and is accordingly guided into the second liquiddrainage bath 25 b.

In a similar way, an upper section of the guard 63 includes a slantedpart 63 a which is tilted diagonally upward from the outward side to theinward side in the radial direction. With the splash guard 6 set to alower position than the second height position (which will hereinafterbe referred to as the “third height position”) during replacingprocessing, the liquid mixture splashing from the rotating substrate Wis caught by the slanted part 63 a and guided into the third liquiddrainage bath 25 c. In more particular words, when the splash guard 6 isat the third height position so that the slanted part 63 a surrounds thesubstrate W which is held by the spin chuck 1, the liquid mixturesplashing from the rotating substrate W drops between the top end of theguard 62 and the top end of the guard 63 and is accordingly guided intothe third liquid drainage bath 25 c.

Further, the splash guard 6 can be set to a lower position than thethird height position (hereinafter be referred to as the “retractposition”), thereby making the spin chuck 1 project beyond the top endof the splash guard 6 and allowing a substrate transporter (not shown)loads the substrate W yet to be processed onto the spin chuck 1 andreceives the processed substrate W from the spin chuck 1.

Next, the operation of the substrate processing apparatus constructed asabove is described in detail with reference to FIGS. 5 to 8. FIG. 5 is aflow chart showing the operation of the substrate processing apparatusof FIG. 1, FIG. 6 is a timing chart showing the operation of thesubstrate processing apparatus of FIG. 1, and FIGS. 7A, 7B, 8A to 8C arediagrams schematically showing the operation of the substrate processingapparatus of FIG. 1. First, the control unit 4 causes the splash guard 6to be positioned at the retract position so that the spin chuck 1projects from the upper end of the splash guard 6. When an unprocessedsubstrate W is loaded into the apparatus by a substrate transporter (notshown) in this state (Step S1), cleaning processings (chemicalprocessing+rinsing processing+replacing processing+pre-dryingprocessing+drying processing) are performed to the substrate W. A finepattern made of poly-Si for instance is formed on the substrate surfaceWf. Accordingly, in this embodiment, the substrate W is loaded into theapparatus with the substrate surface Wf faced up, and is held by thespin chuck 1. The blocking member 9 is at the separated position abovethe spin chuck 1 to avoid the interference with the substrate W.

Subsequently, the control unit 4 causes the splash guard 6 to bearranged at the first height position (position shown in FIG. 1) toperform chemical processing to the substrate W. Specifically, thechemical solution discharging nozzle 3 is moved to the dischargeposition and the substrate W held by the spin chuck 1 is rotated at apredetermined rotating speed (500 rpm for instance) by the driving ofthe chuck rotating mechanism 13 (Step S2). Then, the chemical solutionvalve 31 is opened to supply the hydrofluoric acid as the chemicalsolution from the chemical solution discharging nozzle 3 to thesubstrate surface Wf The hydrofluoric acid supplied to the substratesurface Wf is spread by a centrifugal force, whereby the entiresubstrate surface Wf is chemically processed with the hydrofluoric acid(Step S3). The hydrofluoric acid blown off from the substrate W isguided to the first liquid drainage bath 25 a to be suitably reused.

Upon finishing chemical processing, the chemical solution dischargingnozzle 3 is moved to the standby position. Then, the splash guard 6 isarranged at the second height position to perform rinsing processing as“wet processing” of the invention to the substrate W. Specifically, therinsing liquid valve 83 is opened to discharge the rinsing liquid (DIW)from the rinsing liquid discharge port 96 a of the blocking member 9located at the separated position. Simultaneously with the discharge ofthe rinsing liquid, the blocking member 9 is lowered toward the facingposition to be positioned thereat (blocking-member arranging step). Bysupplying the rinsing liquid to the substrate surface Wf immediatelyafter chemical processing in this way, the substrate surface Wf can bekept wet. This is for the following reason. Specifically, when thehydrofluoric acid is blown off from the substrate W after chemicalprocessing, the drying of the substrate surface Wf starts. As a result,the substrate surface Wf might partly become dry to form stains on thesubstrate surface Wf in some cases. Accordingly, it is essential to keepthe substrate surface Wf wet in order to prevent such partial drying ofthe substrate surface Wf. Further, the nitrogen gas is discharged fromthe gas discharge port 98 a and the outer gas discharge port 99 a of theblocking member 9. Here, the nitrogen gas is mainly discharged from theouter gas discharge port 99 a. In other words, a flow rate balance ofthe nitrogen gas discharged from both discharge ports is adjusted sothat the nitrogen gas is discharged at a very small flow rate from thegas discharge port 98 a while being discharged at a relatively largeflow rate from the outer gas discharge port 99 a.

The rinsing liquid supplied to the substrate surface Wf from the rinsingliquid discharge port 96 a is spread by a centrifugal force resultingfrom the rotation of the substrate W, whereby the substrate surface Wfis entirely rinsed (Step S4: wet processing step). In other words, thehydrofluoric acid remaining to adhere to the substrate surface Wf iswashed away by the rinsing liquid and removed from the substrate surfaceWE The used rinsing liquid blown off from the substrate W is guided tothe second liquid drainage bath 25 b for disposal. Further, the ambientatmosphere of the substrate surface Wf is maintained to be low oxygenconcentration atmosphere by the supply of the nitrogen gas into theclearance space SP (FIG. 7A). Thus, an increase of the dissolved oxygenconcentration of the rinsing liquid can be suppressed. The rotatingspeed of the substrate W during rinsing processing is set, for example,at 100 to 1000 rpm.

Upon performing rinsing processing described above and replacingprocessing and drying processing to be described later, the plate-likemember 90 of the blocking member 9 is rotated in the same rotatingdirection and substantially at the same speed as the substrate W. Thiscan prevent an occurrence of a relative rotating speed differencebetween the lower surface 90 a of the plate-like member 90 and thesubstrate surface Wf, whereby the generation of a swirling air flow canbe suppressed. Thus, it can be prevented that the rinsing liquid and theliquid mixture in the form of mist enter the clearance space SP toadhere to the substrate surface Wf Further, the rinsing liquid and theliquid mixture adhering to the lower surface 90 a can be blown off byrotating the plate-like member 90, thereby preventing the rinsing liquidand the liquid mixture from remaining on the lower surface 90 a.

Upon finishing rinsing processing of a predetermined time, the rinsingliquid valve 83 is closed to stop the discharge of the rinsing liquidfrom the rinsing liquid discharge port 96 a. Then, the control unit 4sets the rotating speed of the substrate W at 500 to 1000 rpm and causesthe splash guard 6 to be arranged at the third height position.Subsequently, the liquid mixture valve 76 is opened to discharge theliquid mixture (IPA+DIW) from the liquid mixture discharge port 97 a.Here, in the cabinet part 70, the liquid mixture whose IPA concentrationis adjusted, for example, to 10% is produced beforehand, and this liquidmixture is discharged toward the substrate surface Wf from the liquidmixture discharge port 97 a. The liquid mixture supplied to thesubstrate surface Wf flows by a centrifugal force acting thereon,thereby flowing into inner gaps of a fine pattern FP formed on thesubstrate surface Wf In this way, the state changes, for example, fromthe one shown in FIG. 7A to the one shown in FIG. 7B, and the rinsingliquid (DIW) adhering to the gaps of the fine pattern FP is securelyreplaced with the liquid mixture (Step S5; replacing step). The usedliquid mixture blown off from the substrate W is guided to the thirdliquid drainage bath 25 c for disposal.

An operation when the rinsing liquid on the substrate surface Wf isreplaced with the liquid mixture is described in detail below. Whenreplacing processing with the liquid mixture is performed to the rinsingliquid on the substrate surface Wf, liquid (liquid mixture) having alower surface tension than the rinsing liquid is supplied to parts ofthe rinsing liquid (DIW) adhering to the substrate surface WE Then, asdescribed in the section “SUMMARY OF THE INVENTION”, a convective flow(Marangoni convective flow) is induced by a surface tension differencebetween the rinsing liquid and the liquid mixture at the respectiveparts on the substrate surface Wf Thus, the agitation of the liquid onthe substrate surface Wf is promoted, thereby increasing a chance of theliquid on the substrate surface Wf being exposed to the ambientatmosphere of the substrate surface Wf As a result, if the oxygenconcentration of the ambient atmosphere is high, dissolved oxygenconcentration in the liquid mixture adhering to the substrate surface Wfincreases as replacing processing proceeds, whereby the substratesurface Wf might be entirely or partly oxidized to form an oxide film orto generate watermarks on the substrate surface Wf in some cases.Contrary to this, in this embodiment, the rinsing liquid on thesubstrate surface Wf is replaced with the liquid mixture under thecondition that the inert gas atmosphere is maintained in the clearancespace SP. Accordingly, the dissolution of oxygen into the liquid mixturecan be reduced and an increase of the dissolved oxygen concentration ofthe liquid mixture can be suppressed.

Subsequently, in this embodiment, the liquid mixture on the substratesurface Wf is removed from the substrate W by performing pre-dryingprocessing to be described below (Step S6). First, the control unit 4stops the rotation of the substrate W or sets the rotating speed of thesubstrate W at or below 100 rpm with the liquid mixture valve 76 opened.By supplying the liquid mixture to the substrate surface Wf with thesubstrate W held stationary or rotated at a relative low speed in thisway, a puddle-shaped solvent layer 41 of the liquid mixture is formed onthe entire substrate surface Wf as shown in FIG. 8A. By forming such apuddle-shaped solvent layer 41 on the substrate surface Wf (puddleprocessing), the adherence of particles to the substrate surface Wf canbe suppressed. Subsequently, the supply of the liquid mixture is stoppedand the nitrogen gas is blown toward the central part of the surface ofthe substrate W from the gas discharge port 98 a. Specifically, the flowrate balance of the nitrogen gas discharged from the gas discharge port98 a and the outer gas discharge port 99 a is so adjusted as to increasethe flow rate of the nitrogen gas discharged from the gas discharge port98 a relative to that of the nitrogen gas discharged from the outer gasdischarge port 99 a. Then, as shown in FIG. 8B, the liquid mixture in acentral part of the solvent layer 41 is pushed away radially outward ofthe substrate W by the nitrogen gas blown to the substrate surface Wffrom the gas discharge port 98 a, thereby forming a hole 42 in thecentral part of the solvent layer 41 and drying a corresponding surfacepart. By continuing to blow the nitrogen gas to the central part of thesurface of the substrate W, the previously formed hole 42 expands indirections toward the rim of the substrate W (transverse directions ofFIG. 8C) and the liquid mixture in the central part of the solvent layer41 is gradually pushed away toward the rim of the substrate to expand adry area as shown in FIG. 8C. Thus, the liquid mixture adhering to thecentral part of the surface of the substrate W can be removed withoutleaving any liquid mixture in the central part of the surface of thesubstrate W.

By performing pre-drying processing as described above, it can beprevented that drops of liquid mixture remain in the central part of thesurface of the substrate W during a period of a drying step (spindrying) and become linear particles to form watermarks on the substratesurface Wf. Specifically, upon removing the liquid mixture adhering tothe substrate surface Wf for drying (spin drying) by rotating thesubstrate W, centrifugal force acting on the liquid mixture is smallertoward the central part of the surface of the substrate W, andaccordingly, the surface of the substrate W is dried from the rim. Atthis time, there were cases where liquid drops remained from the centralpart of the surface of the substrate W to an area around it, ran indirections toward the rim of the substrate W, and watermarks were formedon move traces of the liquid drops. Contrary to this, in thisembodiment, the liquid mixture located in the central part of thesurface of the substrate W is eliminated by forming the hole 42 in thecentral part of the puddle-shaped solvent layer 41 formed on thesubstrate surface Wf beforehand and expanding the hole 42 before thedrying step. Therefore, the formation of watermarks can be securelyprevented.

Upon completing pre-drying processing step in this way, the control unit4 increases the rotating speed of the chuck rotating mechanism 13 torotate the substrate W at higher speed (e.g. 2000 to 3000 rpm). Thus,the liquid mixture adhering to the substrate surface Wf is blown off toperform drying processing (spin drying) to the substrate W (Step S7;drying step). At this time, pattern destruction and watermark formationcan be prevented since the liquid mixture is located in the gaps of thepattern. Further, since the clearance space SP is filled with thenitrogen gas supplied from the gas discharge port 98 a and the outer gasdischarge port 99 a, watermark formation can be more effectivelysuppressed by shortening a drying period and reducing the elution ofoxidizable substances into the liquid component (liquid mixture)adhering to the substrate W. Upon finishing drying processing of thesubstrate W, the control unit 4 controls the chuck rotating mechanism 13to stop the rotation of the substrate W (Step S8). Then, the splashguard 6 is located at the retract position and the spin chuck 1 iscaused to project upward from the splash guard 6. Thereafter, thesubstrate transporter unloads the processed substrate W from theapparatus, thereby finishing a series of cleaning processings for onesubstrate W (Step S9).

As described above, according to this embodiment, rinsing processing isperformed while the nitrogen gas is supplied into the clearance space SPdefined between the blocking member 9 (plate-like member 90) and thesubstrate surface Wf, and replacing processing is performed while thenitrogen gas is supplied into the clearance space SP.

Thus, upon replacing the rinsing liquid adhering to the substratesurface Wf with the liquid mixture, the dissolution of oxygen into theliquid mixture from the ambient atmosphere of the substrate surface Wfcan be reduced. Accordingly, an increase of the dissolved oxygenconcentration of the liquid mixture can be suppressed and the formationof an oxide film or generation of watermarks on the substrate surface Wfcan be securely prevented. Further, since the inert gas atmosphere isset in the clearance space SP while the blocking member 9 (plate-likemember 90) is opposed to the substrate surface Wf, the splash of therinsing liquid or the liquid mixture removed from the substrate surfaceWf back to the substrate surface Wf can be suppressed. Therefore, theadherence of particles to the substrate surface Wf can be reduced.

Further, according to this embodiment, since drying processing isperformed while the nitrogen gas is supplied into the clearance spaceSP, the drying speed of the substrate W is improved, and watermarkformation can be effectively prevented by reducing the oxygenconcentration of the ambient atmosphere of the substrate surface Wfduring drying of the substrate. Further, since a series of processingsfrom rinsing processing to drying processing are performed with theblocking member 9 opposed to the substrate surface Wf and the inert gasatmosphere set in the clearance space SP, the ambient atmosphere of thesubstrate surface Wf can be stably maintained to be the low oxygenconcentration atmosphere. Accordingly, watermark formation can besecurely prevented while pattern destruction is prevented. Further,since a series of processings from rinsing processing to dryingprocessing are performed without (vertically) moving the blocking member9, the processing time can be shortened and the throughput of theapparatus can be improved.

Further, according to this embodiment, pattern destruction can beefficiently prevented while IPA consumption is suppressed as describedbelow since the IPA concentration is set to or below 50%. FIG. 9 is agraph showing the relationship between the IPA concentration and surfacetension y. Horizontal axis of FIG. 9 represents the IPA concentration,wherein the IPA concentration of 0 (vol %) means simple liquid of DIWand IPA concentration of 100 (vol %) means simple liquid of IPA. Thesurface tension y is measured using an LCD-400S produced by KyowaInterface Science Co., Ltd. by a pendant drop method. As is clear fromFIG. 9, it can be understood that, as a mixed amount of IPA into DIW isincreased, the surface tension y of the liquid mixture sharply decreaseswith the increase of the mixed amount of IPA into DIW until the IPAconcentration is around 10%. It can be understood that, at the IPAconcentration of 50% or higher, no large decrease is seen in the surfacetension of the liquid mixture and the surface tension is substantiallyequal to that of the simple liquid of IPA.

Here, in order to effectively prevent pattern destruction, it isimportant to replace the rinsing liquid (DIW) adhering to the gaps ofthe patterns with a substance (low surface-tension solvent) having alower surface tension than the rinsing liquid. In this case, replacingprocessing described above may be performed using 100% of IPA, but arelatively large amount of IPA is necessary if 100% of IPA is suppliedto the substrate surface Wf. Accordingly, it can be thought to supply arelatively small amount of IPA and mix this IPA into DIW from thestandpoint of suppressing the consumption amount of IPA in the case ofusing 100% of IPA. However, if only the relatively small amount of IPAis supplied to the substrate W, even if IPA can be mixed into a surfacelayer portion of DIW adhering to the substrate surface Wf, it isdifficult to introduce IPA into the insides of the pattern gaps.

Contrary to this, by supplying the liquid mixture whose IPAconcentration is 50% or lower to the substrate W, DIW adhering to thepattern gaps can be replaced with the liquid mixture while the IPAconsumption amount is suppressed. The amount of IPA present in thepattern gaps is smaller in this case than in the case of replacingprocessing using 100% of IPA. However, from an evaluation result shownin FIG. 9, even if the IPA concentration is increased above 50%, noconsiderable drop is seen in the surface tension of the liquid mixtureand a large decrease cannot be expected for forces inducing patterndestruction (negative forces produced in the pattern gaps). In otherwords, only the IPA consumption amount increases, but a considerableimprovement cannot be expected for the effect of preventing patterndestruction. Accordingly, by setting the IPA concentration to or below50%, pattern destruction can be efficiently prevented while the IPAconsumption amount is suppressed. Based on this standpoint, the IPAconcentration is preferably set equal to or above 5% and equal to orbelow 10%.

Second Embodiment

FIG. 10 is a timing chart showing the operation of a substrateprocessing apparatus according to a second embodiment of the invention,and FIGS. 11A to 11C are diagrams schematically showing the operation ofthe substrate processing apparatus according to the second embodiment ofthe invention. The substrate processing apparatus according to thesecond embodiment largely differs from the first embodiment in that amajor part of the rinsing liquid adhering to the substrate surface Wf isblown off to be removed with a part thereof left after the rinsing stepand before the replacing step. The other construction and operation arenot described here since being similar to those of the first embodiment.

In this embodiment, upon finishing rinsing processing, the control unit4 sets the rotating speed of the substrate W to 300 to 500 rpm. Althougha relatively large amount of the rinsing liquid (DIW) adheres to thesubstrate surface Wf after rinsing processing (FIG. 11A), a major partof the rinsing liquid on the substrate surface Wf is blown off to beremoved from the substrate surface Wf with a part thereof left byrotating the substrate W for a predetermined time set beforehand (liquidremoving step). Specifically, it becomes a state (surface layer portionremoved state) that only the rinsing liquid at a surface layer portionis removed from the substrate surface Wf with the rinsing liquid in thegaps of the fine pattern FP left (FIG. 11B). As a result, the substratesurface Wf is entirely covered with a liquid film thinner than a liquidfilm (liquid film composed of the rinsing liquid) adhering to thesubstrate surface Wf after rinsing processing. According to the rotatingspeed of the substrate W described above, the surface layer portionremoved state can be realized within a relatively short period of timewhile the drying of the substrate surface Wf is prevented. Accordingly,the period of performing the liquid removing step is, for example, setto 0.5 to 1 sec. Thus, by removing the major part of the rinsing liquidadhering to the substrate surface Wf with the part thereof left prior toreplacement (replacing step) with the liquid mixture (IPA+DIW), theliquid mixture can be efficiently introduced to the insides of thepattern gaps in replacing processing (FIG. 11C), even when fine patternsFP are formed on the substrate surface Wf In other words, by removingthe major part of the rinsing liquid, which has stood as a hindrance tothe introduction of the liquid mixture into the pattern gaps, from thesubstrate surface Wf, the liquid mixture can be highly efficientlyintroduced to the insides of the pattern gaps. Therefore, negativepressures produced in the pattern gaps during the drying of thesubstrate can be reduced to effectively prevent pattern destruction.

On the other hand, the liquid film of the rinsing liquid on thesubstrate surface Wf becomes very thin if the rinsing liquid on thesubstrate surface Wf is roughly removed from the substrate surface Wf asdescribed above. Further, in a case where a pattern exhibitinghydrophobic is present on the substrate surface Wf for example, a partof the substrate surface Wf might be exposed in some cases. At thistime, in the case where oxygen concentration of the ambient atmosphereof the substrate surface Wf is high, the oxygen concentration in therinsing liquid sharply increases by the dissolution of oxygen from theambient atmosphere into the rinsing liquid, thereby making the substratesurface Wf more likely to oxidize. Further, in the case where a part ofthe substrate surface Wf is exposed, the substrate surface Wf might beoxidized in some cases by being directly exposed to the ambientatmosphere. Contrary to this, according to this embodiment, the majorpart of the rinsing liquid on the substrate surface Wf is removed withthe nitrogen gas atmosphere set in the clearance space SP. Thus, a sharpincrease of the dissolved oxygen concentration in the rinsing liquid onthe substrate surface Wf can be suppressed. Accordingly, the oxidationof the substrate surface Wf and watermark formation can be securelyprevented. Further, even if a part of the substrate surface Wf isexposed, it can be prevented to directly oxidize the substrate surfaceWf since the ambient atmosphere of the substrate surface Wf iscontrolled to be the inert gas atmosphere.

Further, according to this embodiment, since the major part of therinsing liquid on the substrate surface Wf is removed, foreign matterssuch as particles are likely to adhere to the substrate surface Wf.However, the inert gas atmosphere is set in the clearance space SP whilethe blocking member 9 is opposed to the substrate surface Wf, hence, theadherence of particles to the substrate surface Wf can be reduced.

Third Embodiment

FIG. 12 is a diagram showing a third embodiment of the substrateprocessing apparatus according to the invention. The substrateprocessing apparatus according to the third embodiment largely differsfrom the first and second embodiments in that the plate-like member 90of the blocking member 9 is rotated as the substrate W rotates in thefirst and second embodiments, whereas the blocking member is arrangedaway from the substrate surface Wf while being held stationary withoutbeing rotated and facing the substrate surface Wf in the thirdembodiment. The other construction and operation are not described heresince being similar to those of the first and second embodiments.

In this embodiment, a blocking member 100 is structured to move upwardand downward between a facing position set in the vicinity of thesurface Wf of the substrate W held by a spin chuck and a separatedposition sufficiently distanced upward from the substrate surface Wf,and is moved upward and downward by driving a blocking-member elevatingmechanism (not shown).

The blocking member 100 includes a disk-shaped plate-like member 101having an aperture in its central part and a spindle 102 mounted on theupper surface of the plate-like member 101 and supporting the plate-likemember 101. A lower surface (bottom surface) 101 a of the plate-likemember 101 serves as a substrate facing surface facing the substratesurface Wf substantially in parallel, and is formed to have a planarsize equal to or larger than the diameter of the substrate W. Thespindle 102 is a bottomed tubular body having an open lower side, and acylindrical inner space IS having a closed upper side is formed by theinner area of the spindle 102 and the aperture of the plate-like member101. Three nozzles, that is, a rinsing liquid nozzle 103 for discharginga rinsing liquid (DIW), a liquid mixture nozzle 104 for discharging aliquid mixture (IPA+DIW) and a gas nozzle 105 for discharging an inertgas such as a nitrogen gas, are inserted through an upper surface 102 aof the spindle 102 toward the substrate surface Wf. The rinsing liquidnozzle 103, the liquid mixture nozzle 104 and the gas nozzle 105respectively include a rinsing liquid discharge port 103 a(corresponding to a “processing liquid discharge port” of theinvention), a liquid mixture discharge port 104 a (corresponding to a“solvent discharge port” of the invention) and a gas discharge port 105a which are open toward a central part of the surface of the substrateW.

Upper limits of distances from the rotation axis J to the rinsing liquiddischarge port 103 a and the liquid mixture discharge port 104 a inhorizontal direction are as in the first and the second embodiments. Therinsing liquid discharge port 103 a and the liquid mixture dischargeport 104 a are preferably arranged at positions radially distanced fromthe rotation axis J as long as the rinsing liquid (DIW) can be suppliedto a rotation center W0 of the substrate W. Particularly, the rinsingliquid discharge port 103 a is preferably arranged at a position distantfrom the rotation axis J from the standpoint of preventing oxidationcaused by the charging of the substrate W. On the other hand, the gasdischarge port 105 a is preferably arranged on or in the vicinity of therotation axis J in order to securely remove a solvent layer of theliquid mixture on the substrate surface Wf from the substrate W by meansof the nitrogen gas.

Further, the nitrogen gas can be supplied toward the substrate surfaceWf from the aperture of the plate-like member 101, that is, a space(inner space IS) surrounding the three nozzles. Specifically, a gassupply passage 106 for supplying the nitrogen gas from a gas supply unit(not shown) into the inner space IS is formed in the spindle 102, thatis, in a side wall of the spindle 102 in this embodiment. Thus, thenitrogen gas is supplied into the clearance space SP defined between theblocking member 100 (plate-like member 101) and the substrate surface Wfwhen the nitrogen gas is pressure-fed from the gas supply unit to theinner space IS.

According to the construction described above, a series of processingsfrom rinsing processing to drying processing are performed with theblocking member 100 (plate-like member 101) opposed to and away from thesubstrate surface Wf in a stationary state without being rotated. Thus,the construction of the apparatus can be simplified as compared to thecase where the plate-like member is rotated. Particularly, according tothis embodiment, degrees of freedom in determining the nozzle borediameters and the arrangement of the three nozzles, that is, the rinsingliquid nozzle 103, the liquid mixture nozzle 104 and the gas nozzle 105can be improved. Specifically, in the case where the plate-like member90 is rotated as described in the first and second embodiments, it isnecessary to keep the clearance between the rotary spindle (rotarymember) 91 and the inner inserted shaft (non-rotary member) 95 sealedfrom the outside and, accordingly, the diameter of the inner insertedshaft 95 is limited to a predetermined size. In other words, if thediameter of the inner inserted shaft 95 is excessively large, it becomesdifficult to seal the clearance between the rotary spindle 91 and theinner inserted shaft 95 from the outside. As a result, there have beenspecific restrictions on the bore diameters and arrangement of thenozzles (fluid supply passages) formed in the inner inserted shaft 95.Contrary to this, according to this embodiment, the bore diameters andarrangement of the three nozzles can be relatively freely set withoutthe restrictions being imposed as described above. Thus, the gas supplypassage 106 can be omitted, for example, by enlarging the bore diameterof the gas nozzle 105 out of the three nozzles. In other words, by meansof the nitrogen gas from the gas nozzle 105, (1) the ambient atmosphereof the substrate surface Wf may be maintained to be an inert gasatmosphere and (2) the solvent layer of the liquid mixture on thesubstrate surface Wf may be removed from the substrate W. In this way,the construction of the apparatus can be further simplified.

Others

The invention is not limited to the embodiments described above but maybe modified in various manners in addition to the embodiments above, tothe extent not deviating from the object of the invention. For instance,although the rinsing liquid discharge port, serving as the “processingliquid discharge port” of the invention, only discharges the rinsingliquid in the above embodiments, it may be constructed that the rinsingliquid and the chemical solution are discharged from the same dischargeport. According to this construction, chemical processing and rinsingprocessing are performed using the chemical solution and the rinsingliquid discharged from a processing liquid discharge port disposed inthe blocking member, whereas replacing processing is performed using theliquid mixture discharged from the solvent discharge port. In thismodification, the chemical solution and the rinsing liquid correspondsto the “processing liquid” of the invention, and chemical processing andrinsing processing correspond to the “predetermined wet processing” ofthe invention.

Further, although the blocking member is formed with one processingliquid discharge port, one solvent discharge port and one gas dischargeport in the above embodiments, the numbers of these discharge ports arearbitrary. For example, only one liquid mixture discharge port 97 a(liquid mixture supply passage 97) is formed in the inner inserted shaft95 in the first embodiment (FIG. 4), but another liquid mixturedischarge port may be formed at a position opposite to the liquidmixture discharge port 97 a with respect to the rotation axis J.According to such a construction, the total aperture area of twodischarge ports formed in the inner inserted shaft 95 can be increasedwhile the bore diameters of the respective liquid mixture dischargeports are made smaller to prevent the drop of the liquid mixture whenthe discharge of the liquid mixture is stopped. As a result, the supplyamount of the liquid mixture per unit time can be increased.Accordingly, upon forming the solvent layer of the liquid mixture on thesubstrate surface Wf for instance, the solvent layer can be formedwithin a relatively short period of time, whereby the throughput of theapparatus can be improved.

Further, although the liquid mixture is produced by mixing the liquid(DIW) having the same composition as the processing liquid and theorganic solvent component (IPA) in the cabinet part 70 in the aboveembodiments, the liquid mixture producing method is not limited to this.For example, the liquid mixture may be produced by mixing the organicsolvent component inline into a liquid supply path for supplying DIWtoward a liquid supply passage (or nozzle) of the blocking member. Aliquid mixture producing unit such as the cabinet part is not limited toinstallation in the substrate processing apparatus, and may supply aliquid mixture produced in another apparatus different from thesubstrate processing apparatus to the substrate surface Wf via theblocking member provided in the substrate processing apparatus.

Although the liquid mixture (IPA+DIW) is used as the low surface-tensionsolvent in the above embodiments, 100% of IPA may be used. Further,instead of the solvent containing the organic solvent component such asIPA, a solvent essentially containing a surfactant may be used.

Further, although the embodiments above use DIW as the rinsing liquid,the rinsing liquid may be a liquid which contains a component which doesnot exert a chemical cleaning effect upon the substrate surface Wf suchas carbonated water (DIW+CO2). In such an instance, a liquid obtained bymixing the organic solvent component with a liquid (carbonated water)whose composition is the same as that of the rinsing liquid adhering tothe substrate surface Wf may be used as the liquid mixture.Alternatively, the liquid mixture may be a mixture of the organicsolvent component and DIW which is a principal component of carbonatedwater, while using carbonated water as the rinsing liquid. Furtheralternatively, the liquid mixture may be a mixture of the organicsolvent component and carbonated water, while using DIW as the rinsingliquid. In essence, the liquid mixture may be a mixture of the organicsolvent component and a liquid whose principal component is the same asthat of the liquid adhering to the substrate surface Wf. Further, therinsing liquid may be, other than DIW and carbonated water, hydrogenwater, diluted ammonia water (having the concentration of around 1 ppmfor instance), diluted hydrochloric acid, or the like.

The present invention is applicable to a substrate processing apparatusand a substrate processing method which performs drying processing to asurface of substrates in general including semiconductor wafers, glasssubstrates for photomasks, glass substrates for liquid crystal displays,glass substrates for plasma displays, substrates for FEDs (fieldemission displays), substrates for optical discs, substrates formagnetic discs, and substrates for magnet-optical discs.

Although the invention has been described with reference to specificembodiments, this description is not meant to be construed in a limitingsense. Various modifications of the disclosed embodiment, as well asother embodiments of the present invention, will become apparent topersons skilled in the art upon reference to the description of theinvention. It is therefore contemplated that the appended claims willcover any such modifications or embodiments as fall within the truescope of the invention.

What is claimed is:
 1. A substrate processing apparatus, comprising: asubstrate holder which holds a substrate in a substantially horizontalposture; a substrate rotating unit which rotates the substrate held bythe substrate holder about a predetermined rotation axis; a blockingmember which includes a plate member, a rotary spindle, an inner shaft,a processing liquid discharge port, a solvent discharge port, a gasdischarge port and an outer gas discharge port, wherein the plate memberis spaced away from a substrate surface while facing the substratesurface to define a clearance space with the substrate surface; therotary spindle is hollow and supports the plate member; the inner shaftis inserted in said hollow rotary spindle; the processing liquiddischarge port is disposed at an end of the inner shaft, and receivesand discharges water or a liquid whose principal component is water as aprocessing liquid to a central part of the substrate surface through theclearance space; the solvent discharge port is disposed at said end ofthe inner shaft and receives and discharges a low surface-tensionsolvent having a lower surface tension than the processing liquid to thecentral part of the substrate surface through the clearance space; thegas discharge port is disposed at the end of the inner shaft near thesolvent discharge port and the processing liquid discharge port, andreceives and discharges an inert gas to the central part of thesubstrate surface; the outer gas discharge port is an aperture definedbetween an inner wall surface of the rotary spindle and an outer wallsurface of the inner shaft, and which receives and discharges an inertgas to the surface of the substrate, and is located radially outward ofand surrounding the processing liquid discharge port, the solventdischarge port and the gas discharge port; and after supplying theprocessing liquid to the substrate surface to perform predetermined wetprocessing to the substrate surface, the low surface-tension solvent issupplied to the substrate surface, and then the low surface-tensionsolvent is removed from the substrate surface to dry the substratesurface, the processing liquid is discharged from the processing liquiddischarge port to perform the wet processing while the inert gas issupplied into the clearance space from the gas discharge port and theouter gas discharge port, and the low surface-tension solvent isdischarged from the solvent discharge port to replace the processingliquid adhering to the substrate surface with the low surface-tensionsolvent while the inert gas is supplied into the clearance space fromthe gas discharge port and the outer gas discharge port.
 2. Thesubstrate processing apparatus of claim 1, wherein a flow rate of theinert gas from the outer gas discharge port is larger than a flow rateof the inert gas from the gas discharge port when the processing liquidis discharged from the processing liquid discharge port and when thesurface-tension solvent is discharged from the solvent discharge port.3. The substrate processing apparatus of claim 1, wherein a flow rate ofthe inert gas from the gas discharge port is larger than a flow rate ofthe inert gas from the outer gas discharge port when the surface-tensionsolvent is removed from the substrate surface.
 4. The substrateprocessing apparatus of claim 1, wherein the substrate rotating unitrotates the substrate to blow the low surface-tension solvent adheringto the substrate surface off from the substrate surface to dry thesubstrate surface while the gas discharge port and the outer gasdischarge port supply the inert gas into the clearance space.
 5. Thesubstrate processing apparatus of claim 1, further comprising ablocking-member rotating unit, wherein the blocking member furtherincludes a substrate facing surface which faces the substrate surface,and the blocking-member rotating unit rotates the substrate facingsurface about the rotation axis of the substrate.
 6. The substrateprocessing apparatus according to claim 1, wherein the end of the innershaft, including the processing liquid discharge port, the solventdischarge port and the gas discharge port is recessed upward from aplane including a lower surface of the plate member of the blockingmember, within the outer gas discharge port, thereby decreasing a flowvelocity of the gas discharge port.
 7. A substrate processing method,comprising the steps of: arranging a blocking member including a platemember spaced away from a substrate surface while facing the substratesurface to define a clearance space with the substrate surface, theblocking member including: a rotary spindle which is hollow and supportsthe plate-like member, and an inner shaft inserted in said hollow rotaryspindle; a processing liquid discharge port which is disposed at an endof the inner shaft, and receives and discharges water or a liquid whoseprincipal component is water as a processing liquid to a central part ofthe substrate surface through the clearance space, the substrate beingheld in a substantially horizontal posture; and a solvent discharge portwhich discharges a low surface-tension solvent having a lower surfacetension than the processing liquid to the central part of the substratesurface through the clearance space, the solvent discharge port beingdisposed at said end of the inner shaft; discharging the processingliquid from the processing liquid discharge port to the substratesurface while the substrate is rotated to perform predetermined wetprocessing to the substrate surface; discharging the low surface-tensionsolvent from the solvent discharge port to the substrate surface wetwith the processing liquid while the substrate is rotated to replace theprocessing liquid adhering to the substrate surface with the lowsurface-tension solvent; and removing the low surface-tension solventfrom the substrate surface after the replacing step to dry the substratesurface, wherein the blocking-member arranging step further includes thesteps of: providing a gas discharge port disposed at the end of theinner shaft near the solvent discharge port and the processing liquiddischarge port which receives and discharges an inert gas to the centralpart of the substrate surface; and an outer gas discharge port which isan aperture defined between an inner wall surface of the rotary spindleand an outer wall surface of the inner shaft, and which receives anddischarges an inert gas to the surface of the substrate, the outer gasdischarge port being located radially outward of and surrounding theprocessing liquid discharge port, the solvent discharge port and the gasdischarge port, wherein the end of the inner shaft, including theprocessing liquid discharge port, the solvent discharge port and the gasdischarge port is recessed upward from a plane including a lower surfaceof the plate member of the blocking member, within the outer gasdischarge port, thereby decreasing a flow velocity of the gas dischargeport; and the inert gas is supplied from the gas discharge port and theouter gas discharge port, in the wet processing step and the replacingstep, into said clearance space defined between the blocking memberarranged in the blocking-member arranging step and the substratesurface.
 8. The substrate processing method of claim 7, wherein, in thedrying step, the substrate is rotated to blow the low surface-tensionsolvent adhering to the substrate surface off from the substrate surfaceto dry the substrate surface while the inert gas is supplied into theclearance space.
 9. The substrate processing method of claim 7, furthercomprising: a liquid removing step of removing a major part of theprocessing liquid adhering to the substrate surface from the substratesurface with a part thereof left after the wet processing step andbefore the replacing step, wherein the inert gas is supplied into theclearance space in the liquid removing step.
 10. The substrateprocessing method of claim 7, wherein, in the replacing step, a liquidmixture, in which a liquid having the same composition as the processingliquid or having the same main component as the processing liquid ismixed with an organic solvent component to be dissolved into the liquidto reduce the surface tension, is discharged from the solvent dischargeport as the low surface-tension solvent.
 11. The substrate processingmethod of claim 10, wherein the percentage by volume of the organicsolvent component contained in the liquid mixture is 50% or less. 12.The substrate processing method of claim 11, wherein the percentage byvolume of the organic solvent component contained in the liquid mixtureis from 5% to 10%.
 13. The substrate processing method of claim 7,wherein the solvent discharge port is provided with a bore diametersmaller than that of the processing liquid discharge port, in saidblocking-member arranging step.